1. Field of the Invention
The present invention relates to detecting apparatuses.
2. Description of Related Art
On an assembly line, a mass of parts, such as fasteners installed in workpieces, may need to be checked whether they are attached to the workpieces properly.
Referring to FIG. 1, a workpiece 90, such as a chassis of a liquid crystal display (LCD), is shown. Electrically conductive fasteners of the workpiece 90, which need to be checked, include two first rivets 6, three second rivets 16, two third rivets 8, a fourth rivet 7, a square piece 188, and a long piece 19. The first rivets 6 and the second rivets 16 are very much alike, but the first rivet 6 is longer. For these fasteners, detected items include: first, checking whether the fasteners are attached to the workpiece 90; second, checking heights of the first rivets 6 and the second rivets 16; third, checking whether the first rivets 6 and the second rivets 16 are attached to the workpiece 90 at predetermined places respectively; and fourth, checking linearity and/or position of the first rivets 6, the second rivets 16, and the third rivet 7.
Typically, the first and third detected items are visually checked by workmen. It is time-consuming and labor-intensive for the workmen, and a long time working will easily cause eye fatigue, which leads to a low checking accuracy and a high checking error rate. This way is inefficient and unfit for mass production.
Referring to FIGS. 2 and 3, checking the heights of the first rivets 6 and the second rivets 16 is done manually by workmen using some tools, such as a height detecting tool 91. Referring particularly to FIG. 3, a distance between a first cantilevered portion of the height detecting tool 91 and a reference plane, dimensioned as Dmax means a maximum permitted height of a part to be checked, while a distance between a second cantilevered portion of the height detecting tool 91 and the reference place, dimensioned as Dmin means a minimum permitted height of the part. In detection, the height detecting tool 91 is advanced towards one of the rivets, such as one rivet 6, with a bottom of the tool 91 abutting on the surface of the workpiece 90. The surface of the workpiece 90 acts as the reference plane. If the first cantilevered portion of the tool 91 corresponding to the Dmax can pass the rivet 6 and the second cantilevered portion thereof corresponding to the Dmin can not pass the rivet 6, a height of the rivet 6 is eligible, otherwise, the height is ineligible. Moreover, different height rivets need different height detecting tools for checking. Thus, checking rivets in this way is complex and labor-intensive for the workmen, and it is inefficient and unfit for mass production.
A detecting tool 92 shown in FIG. 4 is commonly used for checking the accuracy of linearity and/or position of the first rivets 6, the second rivets 16, and the third rivet 7. In use, the workman grips a handle of the tool 92, and moves the tool 92 to the workpiece 90 to see whether the first rivets 6, the second rivets 16, and the third rivet 7 can enter corresponding detecting holes defined in the tool 92. If each rivet enters the corresponding detecting hole smoothly, the linearity and/or position of the rivet is eligible; otherwise, it is ineligible. Checking in this way, it's hard for the workman to align the checking holes of the tool 92 with the rivets of the workpiece 90, and the tool 92 may accidently bump the rivets in aligning process. Moreover, it is hard for the workman to judge contact between a number of walls bounding the corresponding holes and corresponding rivets, which seriously affects a detecting accuracy.
What is desired, therefore, is a detecting apparatus suitable for use in mass production environment, which improves checking efficiency and reliability.